Numerous type of biopsy forceps devices have been developed for in vivo medical diagnosis and treatment of various conditions. Such devices are designed for sampling tissue within the body, for example in endoscopic, laparoscopic and vascular procedures to retrieve biopsy samples for analysis and identification of tissue types. These biopsy forceps devices generally include small cutting jaws at the distal end, operated remotely from the proximal end after the distal end of the device has been positioned or navigated to the site of interest.
One difficulty in using prior art biopsy forceps devices is in knowing for certain the exact positioning of the distal tip, in relation to the suspected disease area, especially when the area of interest is very small. Various types of optical catheters or probes have been developed for use in locating or identifying sites within the body. A method of diagnosing and treating tissue in vivo using an optical guidewire is disclosed in U.S. Pat. No. 5,439,000, assigned to SpectraScience, Inc. One type of prior art system for internal biopsy uses an optical catheter to locate the site, followed by replacement of the optical catheter with a biopsy forceps for taking a sample. However, this can result in errors and uncertainties in the final placement of the biopsy jaws with respect to a previously identified small structure or area.
Other prior art systems have been proposed which use optical viewing or imaging and a cutting device in the same device, to visually locate and then biopsy a suspected area. However, such devices have been hampered by their thickness which is needed to accommodate the imaging system and the cutting actuation system, and which precludes their use in very small areas. Another shortcoming of such prior art systems is the offset or `parallax` between the viewing axis or the imaging system and the cutting position of the biopsy jaws, such that the biopsy sample actually is taken from a zone slightly displaced from the zone being viewed by the optics. This can result in a loss of accuracy in the case of very small structures of interest.